Tracey S. McNamara, D.V.M., Diplomate, A.C.V.P., is a veterinary pathologist and a Professor of Pathology at Western University of Health Sciences College of Veterinary Medicine in Pomona, CA. Dr. McNamara specializes in the recognition and understanding of the diseases of captive and free-ranging wildlife and is best known for her work on the discovery of the West Nile virus in 1999. In 2004 she worked on DTRA’s [Defense Threat Reduction Agency] “Integrated Biosurveillance for Zoonotic Threats” program in Uzbekistan, Kazakhstan and Georgia. She served as lead on a project with Russian colleagues on the “Human-Animal Interface: Improving Biological Threat Detection and Surveillance in Russia” by the Nuclear Threat Initiative’s Global Health and Biosecurity program in Wash. DC. Dr McNamara served as a consultant to the National Biosurveillance Advisory Subcommittee (NBAS) from 2008-2009 and continues to be actively involved in the development of the Nation’s biosurveillance strategy.. She recently gave a TEDxUCLA talk entitled “Canaries in the Coalmine” about continued gaps in biosurveillance for for emerging biological threats. Dr. McNamara is a founding member of the Global Health Security Alliance (GloHSA) working with German/US military, the United Nations, medical intelligence and security sectors. She chaired a panel on “Disease X” at the World Health Summit, Berlin, 2018. She helped organize a meeting at the Salzburg Global Seminar on One Health Metrics in November 2019 and is a Salzburg Fellow. She is actively involved in the One Health movement and advocates for a species neutral approach to the detection of pandemic threats. Most recently, she was asked to be a member of the “Red Dawn Breaking Team” on COVID-19, a group of experts advising the Asst Secretary for Preparedness and Response (ASPR) of the United States.

New York, Summer 1999 In late July 1999, Dr. Tracey S. McNamara, head of the veterinary pathology department at the Bronx Zoo, realized that crows were dying in the neighborhood around the zoo grounds. Dr. McNamara’s crow count had reached forty in August, about the same time that an infectious diseases specialist, [Deborah Susan Asnis (born 1956)], began caring for two elderly patients at the Flushing Hospital, across the East River in Queens.

The first patient, a sixty-year-old man, had been admitted to the hospital on August 12 complaining of three days of fever, weakness, and nausea. On admission, he had a temperature of 103°F and was thought to be suffering from pneumonia. However, on the fourth day he became confused and developed weakness in his limbs. His deep tendon reflexes, like the knee jerk, were feeble, his bladder stopped functioning, and his doctors had to insert a catheter to drain his urine.

Three days later, on August 15, an eighty-year-old man came to the same hospital with fever and weakness. He had collapsed at home and had been resuscitated in the field. On admission to the intensive care unit, he was already being supported by a mechanical ventilator, had a fever of of 104°F, and barely responded to the voices of his doctors. Then, on his third day in the hospital, sudden, total paralysis struck.

Laboratory tests suggested that the patients were suffering from viral encephalitis, and that the weakness was due to some kind of nerve damage, perhaps the Guillain-Barré syndrome. Unlike meningitis, which starts with inflammation limited to the membranes lining the outside of the brain, encephalitis affects the deep brain tissues immediately. Permanent neurological damage or death may result.

One of the most common causes of viral encephalitis is Herpes simplex, the same virus that causes cold sores. But faced with cases of viral encephalitis during the summer, Dr. Asnis also had to consider infections contracted from the bite of a mosquito. The viruses that cause these arthropod-borne infections are called arboviruses, for short. Arboviruses in the United States include eastern equine encephalitis and St. Louis encephalitis. However, these two patients had a striking clinical feature in common that was not typical of any arbovirus with which Dr. Asnis was familiar. They had both been stricken with paralyzing weakness. Dr. Asnis wondered if she were dealing with an entirely new and very dangerous infection.

On Monday, August 23, she telephoned the New York City Health Department. She was put through to Dr. Marcelle Layton, the head of the department’s Bureau of Communicable Diseases. Dr. Layton asked Dr. Asnis to submit samples of blood and of cerebrospinal fluid (the liquid that surrounds the brain, obtained by doing a spinal tap) to the New York State Health Department laboratory in Albany. Dr. Layton then dispatched an epidemiologist to Flushing Hospital to study the background of the two patients in order to determine whether they were linked by any common factors.

On Friday, August 27, [Deborah Susan Asnis (born 1956)] called [Dr. Marcelle C. Layton (born 1958)] to discuss a third possible case, and, while they were on the telephone, another doctor interrupted the call to tell Dr. Asnis about a fourth case. On Saturday, August 28, a fifth case was reported, this time from another hospital in North Queens. Rather than a few sporadic cases, this was beginning to look like a true outbreak.

In addition to looking for clinical clues in the patients’ histories, health department investigators sent samples of blood and cerebrospinal fluid from suspected encephalitis patients to the state laboratory for analysis. On August 31, the eighty-year-old man who had collapsed at home died in the intensive care unit at Flushing hospital. On September 2, one of the second group of patients Dr. Asnis had discussed with Dr. Layton also died. The victim, and eighty-seven-year-old woman, had been admitted to the hospital on August 20 with headache, loose stools, fever, and weakness. The health department obtained fresh brain samples from both of these fatalities and sent them to the state lab.

The first apparent breakthrough in the encephalitis outbreak came from tests of blood and cerebrospinal fluid of this second fatality. While no specific virus had been isolated on culture, the specimens from the eighty-seven-year-old woman did contain a type of antibody suggestive of infection by the St. Louis encephalitis virus, a mosquito-borne arbovirus in the yellow fever family. Though it had never been reported in New York City, cases did occur during the summer months in rural and suburban areas in the southeast. Carried by birds and transmitted by mosquitoes, St. Louis encephalitis is known to cause very severe illness in patients over the age of fifty.

Based on these preliminary test results, Mayor Rudolph W. Giuliani called a news conference in Whitestone, Queens, on September 4 and informed the public of the death of the eighty-seven-year-old woman from St. Louis encephalitis. He noted that it was likely, though not yet confirmed, that an eighty-year-old man who died at Flushing Hospital on August 31 had fallen to the same illness. While there is no specific treatment for St. Louis encephalitis, explained the mayor, the public needed to be informed and familiar with the symptoms of the illness. Mayor Giuliani suggested that New Yorkers remain indoors in the evening and use insect repellent whenever they had to go outside. Finally, the mayor reluctantly declared that the city would need to begin a limited program of nocturnal aerial spraying in northern Queens with the insecticide Malathion. This was a delicate issue; not only would he have to reassure people of the safety of the insecticide, but he would also have to convince everybody in the neighborhoods being sprayed to shut their windows tightly and keep air conditioners off all night despite the heat.

While the public was trying to adjust to the first outbreak of St. Louis encephalitis, the crow epidemic spread over the fence and began killing birds inside the Bronx Zoo. By September 9, Dr. McNamara’s zoo refrigerator contained a dead Guanay cormorant, five Chilean flamingos, a pheasant, and a bald eagle. Upon performing autopsies on the dead birds, she found that they had all died of encephalitis and severe inflammation of the heart. The forty-five-year-old pathologist felt certain that the bird and human encephalitis outbreaks were linked. However, she was not convinced that the infectious agent was St. Louis encephalitis, because birds infected with that virus typically don’t die. On the other hand, she doubted that it was an equine agent, such as eastern equine encephalitis, and South America were affected. Like Dr. Asnis, Dr. McNamara suspected an unusual infectious agent, perhaps one that was newly evolved or recently introduced to this hemisphere. Undeterred by the official announcement, she decided to look further.

On September 9, Dr. McNamara called the Centers for Disease Control and Prevention in Atlanta (CDC) to alert them to a possible link between the avian outbreak and the human cases. She voiced her doubts about the diagnosis of St. Louis encephalitis and arranged to send them samples of bird tissue.

The next day Dr. McNamara also sent tissue samples from two flamingos to the United States Department of Agriculture National Veterinary Services Laboratory in Ames, Iowa. By Monday, September 13, cell cultures in Ames showed that the zoo birds and the wild crows appeared to be dying of the same virus. Although they could not tell exactly what it was, electron microscopy showed it to be the size of a flavivirus, the yellow fever group. Because the Ames laboratory lacked the necessary containment facilities to handle an uncharacterized virus that was potentially dangerous to human beings, they notified the CDC.

Meanwhile, Dr. McNamara’s inquiries had led her to [Dr. Duane J. Gubler (born 1939)], head of the CDC’s arbovirus field station in Fort Collins, Colorado. She sent more specimens and made frequent telephone calls to the Fort Collins laboratory. Later, when asked by the New York Times if it was “persistent sleuthing or persistent pestering” that solved the encephalitis mystery, she replied, “Let’s say the secretaries recognize my voice.”

On September 19, after a week without an answer from the CDC, Dr. McNamara decided to telephone the United States Army Medical Research Institute for Infectious Diseases (USAMRIID) in Maryland. USAMRIID took over the functions of the old biological warfare labs at Fort Detrick, and is now in charge of national defense against biological agents. When she told the army about a possible new virus pathogenic for human beings as well as for birds, they expressed alarm for her safety and asked her to send samples to them immediately. By September 21, USAMRIID had confirmed the presence of a flavivirus in the bird samples and had notified the CDC.

While Dr. McNamara was pursuing a diagnosis of her avian cases, the scientists from the New York State Health Department were following a separate but ultimately converging trail of investigation. During the New York outbreak some of these scientists happened to be attending a conference in Albany, New York. In Albany, they had the brain samples from the fatal encephalitis cases to California and test them using advanced equipment for the study of rare viruses.

In mid-September, Dr. Lipkin began studying the brain samples in his Irvine lab using molecular probes to test the virus’s genetic structure. By September 23, when the human toll had reached nine deaths, he had narrowed his search down to two flaviviruses, one native to Australia, called Kunjin, and West Nile virus. The next day both USAMRIID and his laboratories had completed their tests. The virus was West Nile.

West Nile virus was first isolated in 1937 from the blood of a feverish woman in the West Nile district of Uganda. It is in the yellow fever family, the flaviviruses ( flavi means yellow in Latin)—a group of RNA viruses that also includes Japanese and St. Louis encephalitis, and Dengue fever. It is transmitted by the bite of the female mosquito to its bird host. Humans, horses, and domestic animals may also be infected, but are not important in perpetuating the virus in nature. Found throughout Africa and the Middle East and, less commonly, in Europe, Russia, India, and Indonesia, West Nile encephalitis caused an outbreak in Romania in 1996, in which there were approximately ninety thousand human cases with seventeen deaths. The strain of West Nile that the two labs isolated closely matched a virus found in a sick goose in Israel in 1998. Since West Nile is not generally lethal to its bird hosts, scientists speculate that the Israeli strain that found its way into the United States may have been particularly virulent. Alternatively, birds in the Western Hemisphere, being evolutionary strangers to the virus, may have been more sensitive to its effects.

In human beings, West Nile infection starts out like the flu, with fever and body aches. Patients may then develop some swollen glands, and about half will have a transient rash. Illness is usually mild, either because in areas where the disease is common, people, like birds, have become adapted to it over time, or because infection in these areas occurs in youth, when serious complications are unusual. In some parts of the Nile Delta in Egypt, for example, 40 percent of young adults show evidence on blood tests of past exposure to West Nile, and most do not recall a specific illness.

However, a fascinating experiment conducted in the early 1950s showed that West Nile could produce severe disease in some patients. Researchers working with cancer in laboratory animals had observed that certain viruses seemed to cause animal tumors to regress. In a desperate attempt to help patients with advanced malignancy, researchers injected them with massive doses of West Nile the inoculated patients came down with encephalitis, and one of the patients became paralyzed. Happily, they all recovered from their experimental infection.

We will probably never know how West Nile virus first arrived in the United States in 1999. That the epidemic started in the New York metropolitan area suggests that it was brought to this country by air or ship, rather than as a result of any natural bird migration. The three most likely sources were a recently infected airline passenger from the Near East, who still had the virus circulating in his bloodstream, an infected bird brought into the United States legally or illegally, or an infected mosquito brought by ship or airplane.

The New York patients were not suffering from a new disease then, but were the first cases of an old disease occurring in a new place. Based on past experience with West Nile, the investigators suspected that a wider outbreak of the disease was going on. Therefore, public health authorities asked all the hospitals in New York City and neighboring counties to report any suspected cases of viral infections of the central nervous system, including patients hospitalized back to August 1, 1999. They devised tests for West Nile antibodies in serum and cerebrospinal fluid. In that first year of the epidemic, the investigation identified fifty-nine patients hospitalized with West Nile infection in the New York metropolitan area, with seven fatalities. The median age of hospitalized patients was seventy-one years, but patients as young as five and as old as ninety were also affected. The risk of death was especially high in patients seventy-five years of age or older. In the first outbreak, thirty-two of the fifty-nine patients lived in the New York borough of Queens, and none of the cases occurred outside New York State. An ominous finding, however, was that infected birds were found in three nearby states—Connecticut, Maryland, and New Jersey.

Most North American birds proved more resistant to the virus than the crow; house sparrows and other migratory species can live with West Nile multiplying in their blood streams. Even as scientists were struggling to identify the virus during the fall of 1999, the bird migration season had already begun. West Nile was winging its way in a thousand birds to a thousand destinations.

The last recorded patient that first year fell ill on September 22, and the human epidemic ended when the weather turned cold and the mosquitoes stopped biting. But it was already clear that West Nile could not be contained by spraying affected neighborhoods, or even by spraying whole states. West Nile was sure to return with each summer’s birds and mosquitoes. Scientists only hoped spread through the human population would be slow.

In preparation for the 2000 West Nile season, seventeen eastern states along the Atlantic and Gulf coasts, New York City, and the District of Columbia began West Nile surveillance. Beginning in the winter they collected mosquitoes, set up sentinel chicken flocks, sampled wild birds, and collected serum from horses and other mammals. In 2000, West Nile was found in twelve states, with human cases occurring in three. There were twenty-one cases of acute West Nile infection, with nineteen patients hospitalized, one death, and one patient left in a “vegetative state.” Although the number of people identified with severe disease was less than in 1999, CDC estimated that approximately two thousand people had milder forms of the disease. Ominously, animal surveillance found over four thousand dead birds with West Nile, and, in addition, sixty-five horses were identified with severe neurological diseases. West Nile was detected in fourteen bats, four rodents, three rabbits, two cats, and two raccoons in New York, and in a skunk in Connecticut. During this outbreak, the CDC noted that severe disease in people in any given county was always preceded by fatal cases in birds, confirming the value of avian surveillance. 

The mosquito-borne illness that has killed three people in New York City may not be St. Louis encephalitis, as experts have thought, but rather a similar disease that has never been diagnosed in the Western Hemisphere, Government scientists said yesterday.

The disease, West Nile virus, was discovered this week in dozens of birds that died in and around the Bronx Zoo this summer. The virus is indigenous to Asia and northern and eastern Africa and occasionally makes its way to Europe, but has never been found in birds or people in this hemisphere, said [Dr. Duane J. Gubler (born 1939)], the director of the division of vector-borne infectious disease at the Federal Centers for Disease Control and Prevention.

Before yesterday, the illness that has infected at least 14 people in New York City and 4 in Westchester County was believed to be St. Louis encephalitis, which was surprising enough because that disease is rarely found outside the Southeastern United States.

Scores of tests will need to be completed before health officials will be able to say for sure whether the infections were caused by some type of West Nile virus or St. Louis encephalitis. Officials at the C.D.C. said they hope to have the tests completed sometime next week.

But the discovery of the West Nile strain in the birds has cast some doubt on the original diagnosis, officials said. ''West Nile virus is closely related to St. Louis encephalitis, the virus we thought was causing the outbreak,'' [Dr. Duane J. Gubler (born 1939)] said. The discovery of the dead birds, he said, ''has caused some confusion as to whether that is true now.''

The finding of the West Nile virus in New York stunned experts, who have no theory so far on how the strain found its way here.

If officials confirm that the disease that sickened New Yorkers was the West Nile virus, it would have no practical effect on those who have fallen sick, or on the efforts to control the disease from spreading. Both illnesses are transmitted from birds to mosquitoes to people by the same type of mosquitoes, and the same insecticide would be used.

The symptoms of both illnesses are virtually the same and are usually mild, though in rare cases they can cause neurological disorders and even death.

Experts said those severe cases -- which generally involve the elderly, children under 5 and those with compromised immune systems -- are even less frequent with West Nile virus.

''The important message to get across is that all the public health and responsive measures implemented are the same,'' said Tom Skinner, a spokesman at the C.D.C.

But from an epidemiological standpoint, the discovery of West Nile virus in New York is remarkable. ''This is exciting,'' Dr. Gubler said. ''We prefer it didn't occur, but it is interesting.''

''What we are seeing in the waning years of the late 20th century is the transport and movement of these viruses in new areas,'' he added. ''And you get a virus moving into a new area, the entire mosquito population is susceptible.''

Yesterday, two elderly women were added to the list of confirmed cases of the mosquito-borne illness. One of the women, who is 90 years old and in critical condition, was the first case to be confirmed in Manhattan since the outbreak began in August. Officials said the woman, who lived near Central Park, apparently contracted the virus in Manhattan, but it was not clear where.

Now, old and new blood samples from people with symptoms, trapped mosquitoes, as well as roughly 450 birds will be examined to see whether the West Nile virus found in the birds was what has caused the New Yorkers to become ill.

It is not surprising that the diagnosis of those who have taken ill could have been mistaken, experts said -- the illnesses appear very similar, and few would have thought to look for an illness whose closest brush with this country was in France in the 1960's. The worst modern outbreak of the West Nile virus was in Romania in 1996, when 90,000 cases were confirmed and 17 people died.

The discovery of the West Nile virus came about in large part by some dogged sleuthing by a head of the department of pathology at the Bronx Zoo, Federal officials said. That pathologist, Tracey McNamara, said she became concerned in late July when she heard that a large number of crows had been dying around the zoo. Then, birds at the zoo began to go. Over Labor Day weekend, the zoo lost a Guanay Cormorant, three Chilean flamingos, a pheasant and a bald eagle. Because these deaths followed those of some crows, experts strongly doubt that the disease originated in the zoo.

Autopsies of the birds revealed streaking in the heart and brain hemorrhages. An equine encephalitis was suspected, but Dr. McNamara was skeptical, because the emus in her care, which are very susceptible to that illness, were thriving.

When two more flamingos died on Sept. 9, she sent samples to laboratories of the United States Department of Agriculture, which ruled out all the common bird viruses. Stymied, they called in an equine virologist to do further testing. The C.D.C. and doctors at an Army lab in Maryland were also sent samples.

Yesterday, the C.D.C. discovered the West Nile virus link.''Everyone was shocked,'' Dr. McNamara said. ''It's possible it came in with a human being or a smuggled bird, and I am not at all certain it will ever be established how it got here.''

The Mayor's Office of Emergency Management, which has been in charge of the spraying, would not comment on the C.D.C. news.

As Westchester County prepared to continue its spraying last night, many Jewish residents voiced concern that such efforts would interfere with the start of the Succoth holiday, which requires observants to sit in an open air tent or hut to take their evening meal.

Victoria Hochman, a spokeswoman for the Westchester County Executive's office, said the agency was aware of the holiday and had contacted regional Jewish centers, ''but we have decided it is a health emergency and we have to go with the spraying for the good of everyone.''

Connecticut officials said they would not spray any more until receiving results from recent mosquito testing, and New York City completed its second round on Thursday night and would also wait to see when and if it would need to spray again.

The mosquito-borne illness that has killed three people in New York City is not St. Louis encephalitis, but a similar disease that has never before been found in the Western Hemisphere, health officials said early this morning.

Scientists in two states who have been examining brain tissue from the people killed by the outbreak of encephalitis confirmed that it was caused either by West Nile virus, from Africa, or Kunjin virus, a variant that is found only in Australia.

Since last month, 14 people in New York City and Westchester County have been diagnosed with encephalitis, although it was unclear whether the two strains identified today are responsible for all the cases.

An official with the Centers for Disease Control and Prevention in Atlanta, and a researcher at the University of California at Irvine said this morning that the closely related strains had been positively identified in the brain matter of New York City residents killed by encephalitis. Until now, neither strain had been found in birds or people in this hemisphere.

[Dr. Duane J. Gubler (born 1939)], director of the C.D.C.'s division of vector-borne infectious diseases, said that the agency's lab found the West Nile virus in the brain of one of the victims early last week. ''It was a total surprise to us,'' he said. ''There was no reason to suspect that we'd find West Nile here.''

[Dr. Walter Ian Lipkin (born 1952)], the director of the Emerging Diseases Laboratory at the University of California at Irvine, said his colleagues had identified the virus in the brains of three victims from Queens that had been sent to his lab last week. ''It's very odd that they've been found here,'' he said. ''On the other hand, viruses evolve and they have the capacity to adapt themselves.'' Dr. Lipkin emphasized that the genetic difference between West Nile virus and Kunjin virus is so slight that the two are practically the same strain.

Until yesterday, New York health officials said they had found the West Nile virus only in birds that had died in and around the Bronx Zoo. But this morning, after the C.D.C confirmed the discovery of the virus in humans, a state official acknowledged that officials had known about the findings of [Dr. Walter Ian Lipkin (born 1952)] and Dr. Gubler for several days, but wanted to conduct more tests.

John Signor, a State Health Department spokesman, said the ageny was planning to release the information tomorrow after more testing confirmed the earlier findings. ''The identification of a virus is a complex process,'' he said. ''We felt more testing needed to be done.''

Despite the discovery that the encephalitis outbreak had been caused by a different virus, officials said that the public health measures undertaken to date would not change: the spraying of mosquitos and warnings to reduce exposure to the insects remains. Mr. Signor said that the treatment for those already infected with the disease would remain the same.

The Federal Centers for Disease Control and Prevention said Friday night that its scientists had identified a West Nile-like virus in four birds from New York that they had tested in their laboratory in Fort Collins, Colo.

The birds included two flamingos and an Asian pheasant from the Bronx Zoo, and a crow reported to be from Scarsdale, said Kristine Smith, a spokeswoman for the New York State Health Department.

Yesterday, city health officials continued collecting dead birds, which they had started to do on Friday. Special telephone lines and asked residents to call in sightings of dead birds. By 4 P.M. yesterday, the City Health Department had received two dozen reports of dead birds in all five boroughs, and sent out staff members from its pest control division to retrieve specimens, said a spokeswoman, Sandra Mullen.

''The birds will be kept on dry ice and brought to our Bureau of Laboratories,'' she said, adding that most of the dead birds reported were crows, which have been dying in large numbers since the beginning of the outbreak. Health officials in Suffolk County collected five dead crows on Friday, and sent them for analysis to the State Department of Environmental Conservation yesterday, said the director of public health, Mahfouz Zaki.

And after receiving reports at 5:30 P.M. on Friday that earlier samples from dead crows tested positive for an encephalitis-like disease, they sprayed South Huntington and Huntington Station with pesticides.

In Manhattan, a team from the Parks Department swept through Central Park on Friday night searching for dead birds but found none, said Parks Commissioner Henry J. Stern. He said that more teams would be dispatched, but that all park staff members had been notified and were on the lookout.

News that the infection was either West Nile virus or an Australian variant has deepened an epidemiological mystery that began in July with the deaths of numerous crows around the Bronx Zoo.

A pathologist at the zoo, Tracey McNamara, first noticed that large numbers of crows were dying, reaching 40 by August. Then, birds at the zoo, including a guanay cormorant, three Chilean flamingos, a pheasant and a bald eagle, died.

Though the symptoms of both diseases are similar, and the steps to combat them are the same, the mosquitoes that carry them can differ, health officials said.

Ms. Smith of the State Health Department said the mosquitoes that carry St. Louis encephalitis and West Nile viruses, the Culex pipiens, are generally active from dusk to dawn. But another type of mosquito known to carry the West Nile virus, the Aedes vexans, is also active during the day, she said.

The symptoms of both illnesses are usually mild, but in some cases can cause neurological disorders and even death.

When you hear hoofbeats, don't think of zebras.

To doctors, the axiom is a call to focus on common ailments and not waste time on the exotic. But on those rare occasions when they do detect a zebra, doctors say they need to take extra steps in their investigation to make sure they have identified the right one.

A case in point is the encephalitis outbreak that is blamed for at least three deaths in New York City. Earlier this month, the Centers for Disease Control and Prevention in Atlanta and the New York City Health Department said the cause was the mosquito-borne St. Louis virus, which had never been identified in New York City before.

But last weekend the C.D.C., responding to findings from laboratory tests performed by Dr. Tracey McNamara, a pathologist at the Bronx Zoo, announced that the outbreak was caused by an even rarer zebra: the West Nile virus from Africa. [Dr. Walter Ian Lipkin (born 1952)], of the Emerging Diseases Laboratory at the University of California at Irvine, confirmed the findings.

The viruses are closely related, causing virtually the same type of inflammation of the brain. But the West Nile virus had never before been detected in the Western Hemisphere.

'C.D.C. would not have made the diagnosis of West Nile virus as quickly without Dr. McNamara's persistent medical sleuthing,'' [Dr. Duane J. Gubler (born 1939)], the head of the C.D.C.'s arbovirus field station in Fort Collins, Colo., said in an interview.

The change in diagnosis, though not important in terms of the spraying and other public health measures taken to combat the outbreak, was scientifically embarrassing to the C.D.C., the premier Federal agency that is responsible for tracking infectious diseases in this country.

In recent years, C.D.C. and other health officials have led a campaign against the threat of new and emerging infections, warning doctors to expect more infectious disease ''zebras,'' like the sudden appearance of old microbes in new areas.

In fact, health officials thought they had scored a coup when they diagnosed the mysterious illness as the St. Louis virus. The disease is usually found in the Southeastern states, and humans are usually bystanders in such infections. Birds are the principal reservoir for the arboviruses, but they do not become sick. Instead, mosquitoes transmit the viruses to people, who may become ill.

In hindsight, the concurrent deaths of an unusual number of birds in the city has turned out to be an important but underestimated clue. Federal and local medical sleuths did not immediately relate the bird die-off to the human outbreak because West Nile, St. Louis and similar encephalitis viruses generally do not kill birds.

Now the C.D.C. is retesting blood and spinal fluid from patients who had symptoms of encephalitis and who did not show evidence of the St. Louis virus.

The new findings mean that health workers need to investigate a number of other possibilities, [Dr. Duane J. Gubler (born 1939)] said.

A critical one is that the C.D.C. can no longer be certain that the West Nile virus has never been present in the United States, because the Federal scientists never specifically checked for it in earlier outbreaks and individual cases. In testing mosquitoes and specimens from humans with encephalitis, the C.D.C. routinely checks all types of viral encephalitis known to have caused infection in the Western Hemisphere, Dr. Gubler said.

There can be considerable overlap in findings from the laboratory tests unless extra steps are taken to distinguish between the many types of encephalitis-causing arboviruses. In a sense they are all one virus, but with many variations that can be detected in the laboratory. The encephalitis they cause is the same disease, although there can be subtle differences in the type of brain damage they produce.

The viruses occur in different geographic areas, and by scientific custom they are named for the area where they were discovered. They include Murray Valley encephalitis in Australia, Japanese encephalitis, and Rocio virus in Brazil and Argentina. They are distinguished in the laboratory by small differences in the proteins in the covering of the virus known as its envelope.

''We don't include West Nile, Japanese and other encephalitis viruses because they have never been known to be here,'' Dr. Gubler said, adding that in the New York outbreak, ''we had tunnel vision on St. Louis virus, because all the clinical, epidemiological, laboratory and geographic features pointed to St. Louis.''

''We've learned a lesson here,'' Dr. Gubler continued. ''We've got to be more open-minded.

''Once we get past this crisis, we are going to have to go back and check specimens from C.D.C. and state health departments to see if it has been here, and if so for how long.''

The West Nile virus was discovered in 1937 in Uganda. Since then ''it has rarely reared its head,'' [Dr. Duane J. Gubler (born 1939)] said, though outbreaks and occasional cases have been reported from Israel, France, Romania and elsewhere in Europe. Presumably the virus was carried northward by birds migrating from Africa.

After a nearly two-decade silence, West Nile virus caused a large outbreak in Romania in 1996. This year, West Nile virus apparently caused illness among humans in Volgograd, Russia, though Dr. Gubler said he had received no reply to an inquiry he has made to Russian scientists about the outbreak. Lack of communication among scientists thwarts efforts to learn why a virus is spreading.

When birds began dying in and near the Bronx Zoo, Dr. McNamara, the pathologist there, initially thought the deaths might be a result of viruses that cause avian influenza, Newcastle disease, fowl cholera or Eastern equine encephalitis, Dr. Gubler said.

Dr. McNamara sent the specimens to the Department of Agriculture Laboratory at Ames, Iowa, where scientists eliminated those candidates. Because the Ames laboratory lacked the material to test for the pertinent arboviruses, they forwarded the specimens to the C.D.C., Dr. Gubler said.

Dr. Gubler said scientists also needed to investigate whether the deaths of the birds indicated that West Nile virus had become more virulent.

Also, the virus has been shown to stay in the blood of humans longer than other types of encephalitis virus, so that mosquitoes are more likely to pick it up and transmit it to other humans. But whether such transmissions occur on a regular basis is not known, Dr. Gubler said.

A main focus will be to prevent a recurrence of the outbreak in New York next summer. Scientists do not know whether the virus can persist in infected mosquitoes while they hibernate over the winter, Dr. Gubler said. In the absence of definitive information, health officials will consider the need to begin control of storm drains to decrease the probability of infected mosquitoes' surviving over the winter.

On Sept. 23, nearly three weeks after Mayor Rudolph W. Giuliani announced that New York was being attacked by a mosquito-borne virus often found in the Southern United States, senior Federal health officials convened a conference call to hear some startling news.

The scientist who initially identified the virus as St. Louis encephalitis said he had changed his mind, an official who was present said. It was probably a form of West Nile virus, a disease never before seen in the Western hemisphere.

Stunned by the sudden turn, senior officials at the Federal Centers for Disease Control and Prevention peppered their colleague with questions. Was he sure? What testing was done? Was it repeated?

The officials decided not to inform New York of the new finding immediately. They sent the scientist, [Dr. Duane J. Gubler (born 1939)], back to his laboratory in Fort Collins, Colo., to do more tests. He reconfirmed the conclusion, and the next morning, calls went out to New York City.

Federal public health officials were chagrined but not overly worried by the sudden switch in diagnosis. West Nile virus is slightly less virulent than St. Louis encephalitis, and the city was already eradicating the mosquitoes that transmitted the disease, whatever it was.

But the announcement caused concern among many of the scientists and Government officials who are working to strengthen the nation's defenses against biological warfare. They saw the New York outbreak as a dress rehearsal, a test of how public health officials could detect and deal with the sudden spread of a disease not typically found in the United States. To them, the missed diagnosis was unnerving.

''The encephalitis outbreak in New York is a powerful lesson for public health authorities,'' said Alan P. Zelicoff, a senior scientist at the Federal Center for National Security and Arms Control at Sandia National Laboratories in New Mexico. ''It is a sobering, not so reassuring, demonstration of the inadequacies of the U.S. detection network for emerging diseases.''

Local and Federal officials agree there is much to be learned from New York's experience that can be applied equally to defense against biological warfare and the emerging need to deal with the global spread of virulent disease.

While the public health system performed well in many regards, officials point to several key missteps. For instance, in testing samples from the initial victims, the C.D.C. screened only for six viruses common in this country. The scientists did not test for several that have been linked to foreign epidemics or germ warfare.

In addition, the scientist holding a key clue to the true identity of the virus, a bird specialist who had noticed the unexplained deaths of crows near the Bronx Zoo, could not get anyone at the C.D.C. to return her calls for a week. In the end, she turned to several other Government laboratories, including a military research center, to confirm her suspicions that the C.D.C. had the wrong virus.

Finally, the myriad state, local and Federal agencies involved in the investigation did not always communicate well with one another.

''We've learned about the need for, and benefits of, improvements in laboratory coordination,'' said Scott Lillibridge, who leads the C.D.C.'s Bioterrorism Preparedness and Response Program. ''We've also learned how helpful surveillance can be, particularly in beginning to track the beginning, extent or progress of an infectious disease outbreak.''

Over the past several years, the Federal Government has invested hundreds of millions of dollars on a national program to defend against biological terrorism. Several officials said that in light of New York's experiences, much more money should be invested in the public health systems detecting epidemics.

The Discovery : 2 Elderly Patients Sound an Alarm

On Aug. 23, Dr. Deborah S. Asnis, an infectious disease specialist at Flushing Hospital Medical Center in Queens, called the city's Health Department with some distressing news -- two elderly patients had come in with symptoms that looked like a neurological illness -- fever, muscle weakness and confusion.

Dr. [Dr. Marcelle C. Layton (born 1958)], who heads the Health Department's Bureau of Communicable Diseases, told Dr. Asnis to send samples to the State Department of Health, and then called the C.D.C. to warn them that something -- maybe botulism -- was happening in New York City. As the week went on, the number of sick people was starting to mount.

The case was assigned to Dr. Gubler, one of the C.D.C.'s experts on diseases spread by insects. His suspicions focused on St. Louis encephalitis, which is often found in the Southeastern United States.

To confirm his theory,  [Dr. Duane J. Gubler (born 1939)], tested the samples for antibodies against six viruses transmitted by insects and commonly found in the United States. The tests came back positive for St. Louis encephalitis, a close relative of West Nile fever.

The C.D.C. announced on Sept. 3 that tests of blood and spinal fluid had confirmed Dr. Gubler's suspicion. The Mayor called a hasty news conference in Queens. His office of emergency management took the helm and began a $6 million campaign to wipe out New York's mosquitoes.

Within days, New York City had practically cornered the nation's supply of insect repellent, and 250,000 brochures about the disease were printed and distributed, along with the free repellent, by 500 city employees.

And New Yorkers quickly began to debate which thing unknown to their region they feared the most -- St. Louis encephalitis, or malathion, the insecticide that began to rain down from clacking helicopters.

At the Bronx Zoo, officials were worrying about what seemed to be a serious, but separate biological event. Since July, zoo officials had been receiving calls from people in the Bronx and Queens about dead birds. Four days after the city's St. Louis encephalitis announcement, several exotic birds at the zoo were dead. But not emus. And that made Tracey S. McNamara nervous.

Dr. McNamara, who is the head of the department of pathology at the zoo, knew that St. Louis encephalitis, which is carried by birds and transmitted through mosquitoes, does not normally kill the birds.

She considered the possibility that the birds were being killed by another common form of encephalitis. But that disease is deadly to emus, which were thriving. Something much more complicated was afoot, she reasoned.

The pathologist took to her lab, spending 12 hours a day analyzing bird samples. What she found was so disturbing, she said, that she called the C.D.C to alert them. The dead birds were bleeding from the brain and had badly damaged hearts. Was a similar virus infecting people?

''We had dead people and dead birds and I thought we needed to pursue this,'' she said.

She also contacted the National Veterinary Services Lab in Ames, Iowa, part of the United States Department of Agriculture, to study the samples. Around the same time, Ward Stone, the chief wildlife pathologist for the State Department of Environmental Conservation, began noticing large numbers of dead crows, and alerted his counterparts in New Jersey and Connecticut that something strange was happening to the local bird population.

While the C.D.C. agreed to take some of Dr. McNamara's samples, agency workers then did not return her daily calls for a week. ''I got voice mail,'' she said. In fairness, she acknowledged, dead people were taking precedence.

But the agency seemed slow to grasp the possible link to the birds' illness. Dr. McNamara is circumspect about criticizing her colleagues at the C.D.C., but she said, ''I would say a lesson to be learned was that there was some tunnel vision.''

In the Federal Government's dress rehearsals of how a city might detect and handle a sudden outbreak of disease, officials had foreseen many different scenarios. But no one had anticipated an outbreak in which crucial evidence would be uncovered by a wildlife specialist.

''How we respond to introduced diseases in the wildlife perspective is not very well resolved,'' said Michael Samuel, a research project leader at the National Wildlife Health Center, a unit of the Department of Interior, which is also researching New York's outbreak. ''I don't know that we as a nation have a contingency plan in place.''

Dr. Stephen Ostroff, the acting deputy director for science and public health at the C.D.C., said that confusion is a normal part of an emerging diseases investigation.

''Anyone who continues to maintain that there was some mistake here doesn't understand the way science proceeds in outbreak investigations,'' Dr. Ostroff said. ''You won't hear any apologies from me.'' He said he was not aware of Dr. McNamara's repeated attempts to reach C.D.C. officials.

The Breakthrough : Military Minds Turn to Outbreak

Back in the Bronx, Dr. McNamara was getting impatient. The veterinary lab in Ames had already exhausted its capabilities, but could not specifically identify the strange virus that was killing the birds.

Dr. McNamara sent more samples to the C.D.C., but she also put in a call to the United States Army Medical Research Institute of Infectious Diseases, looking for a favor.

Could the laboratory, which does not usually get involved with civilian requests, take a peek at her samples? Dr. McNamara, it turned out, had some chits to call in. She had recently attended the wedding of the pathologist who performs such tests. The lab agreed to take a look.

The system was working, after a fashion. The military's finest minds on bioterrorism had turned to New York's outbreak.

On Sept. 21, Dr. McNamara sent the samples to the lab by overnight mail. Within a day, the Army's unit, which is based in Fort Detrick, Md., confirmed that a virus of a very different sort was killing birds.

Meanwhile, the C.D.C. was beginning to make the connections. On the same day, officials at the agency called Dr. McNamara and said they wanted more material. She sent it out that evening.

On Sept. 24, scientists at the Army lab told her that the tests of bird samples for West Nile virus ''really lit up,'' Dr. McNamara said.

The C.D.C., with help from each of the labs involved, had come to the same conclusion. That day, the agency announced that birds were dying in New York City, and a West Nile-like virus was the reason. The scientists strongly suspected that the humans had been killed by the same virus, but had yet to confirm it.

The answer came, strangely enough, from California. The New York State Department of Health, without telling the C.D.C., sent some of the brain tissue from people believed to have died of St. Louis encephalitis to a lab run by [Dr. Walter Ian Lipkin (born 1952)], a scientist at the University of California in Irvine who had bumped into state scientists at a conference in Albany.

On Sept. 24, [Dr. Walter Ian Lipkin (born 1952)] found that a form of West Nile virus -- which the C.D.C. now believes is similar to a strain previously found in Europe -- had sickened the New York patients. Soon after, the C.D.C. reached the same conclusion.

The words ''West Nile virus'' had little significance in New York. But in Washington, they raised red flags among American intelligence officials who follow bioterrorism, an incident reported by this week's New Yorker magazine.

In April, a supposed associate of Saddam Hussein published a book in Britain in which he claimed that the Iraqi leader had threatened in 1997 to unleash a form of West Nile virus against his enemies.

A closer look at the Iraqi biological weapons program found no evidence that Baghdad had ever experimented with the virus and intelligence officials, along with arms inspectors who had visited Iraq's laboratories, concluded the report was baseless.

Last night, the C.D.C. issued a statement saying it believed the West Nile outbreak was the work of ''Mother Nature.''

The eerie coincidence underscored what officials said was a new reality.

''Sadly the world has changed. The threat of bioterrorism is real and growing,'' said Dr. Margaret Hamburg, an assistant secretary at the Department of Health and Human Services who was previously head of the New York City Health Department. ''Whenever a new or unexpected disease emerges in an outbreak such as this, it would be irresponsible not to at least consider the possibility of bioterrorism.''

Congress, the officials said, has been slow to spend money on detecting outbreaks, even as they invest hundreds of millions in other bio-defense efforts and vaccines.

This year, lawmakers for the first time approved $120 million to strengthen the C.D.C.'s programs for education and monitoring disease. However, the $40 million set aside for improving state and local health detection was only disbursed late last month, as a West Nile-like virus was spreading through New York.

''We're spending hundreds of millions on questionable stockpiles of vaccines and antibiotics,'' said Dr. Zelicoff, the scientist at the Sandia Laboratory. ''We should be improving the ability of local public health officials to recognize and report strange illnesses to a central authority that can quickly tell them what to do about it.''

Millions of deaths each year can be traced back to animal diseases, experts say.

Early cases of COVID-19 are believed to be linked to a live-animal market in Wuhan, China.

Even as the COVID-19 pandemic rages on, experts are warning that the next pandemic could arrive at any moment, and again, it could come from animals. To prevent history from repeating itself, experts say governments need to start investing heavily in pandemic prevention efforts.

That means deploying teams of biologists, zoologists and veterinarians to begin monitoring animals and the people who interact with them -- an army of scientists tasked with stamping out the next deadly virus before an animal disease balloons into a global pandemic.

According to the World Health Organization, approximately 1 billion cases and millions of deaths each year can be traced back to diseases originating from animal populations.

In the past three decades, researchers have found more than 30 bacteria or viruses that are capable of infecting humans. Over three quarters of those are believed to have come from animal populations.

And while the current pandemic may feel like a very rare happening, scientists say the pace of these pandemics is accelerating dramatically thanks to humans' ever-encroaching proximity to wildlife.

Beginning with SARS almost two decades ago and followed by West Nile, Ebola, Zika and currently, COVID-19, many of these pandemics originated with species of bats, and can be spread between people through coughing and sneezing or through insects such as mosquitoes.

"The time between these outbreaks is getting shorter and shorter," said [Dr. Tracey S. McNamara (born 1954)], a professor of pathology at Western University of Health Sciences College of Veterinary Medicine.

And it's becoming increasingly clear that these viruses aren't just a threat to our health -- they're also a threat to the global economy.

"We are only able to sustain an outbreak maybe once every decade," said [Dr. Peter Daszak (born 1965)], president of EcoHealth Alliance. "The rate we are going is not sustainable."

The COVID-19 pandemic did not surprise McNamara and Daszak. For decades, they, and other scientists, have been warning politicians and the public that wild and domestic animals -- and the viruses they carry -- pose a threat to humanity.

Without proper monitoring and surveillance of these creatures, they warned, we would be ill-prepared to stop a virus from spreading across the globe. [Dr. Tracey S. McNamara (born 1954)] was part of the "Red Dawn" group, a now-infamous email chain of top scientists that asked powerful U.S. government officials to mount a more vigorous domestic defense back when coronavirus was still considered a problem confined to China's borders.

And Daszak, who has spent much of his career hunting for the next pandemic-causing virus in bat caves in Asia, saw U.S. government funding for his science slashed back in April.

Perhaps most ominously, a U.S.-funded early-warning system called PREDICT, which was launched in 2009 in response to the H5N1 bird flu outbreak, saw its funding quietly lapse in late 2019.  [Dr. Peter Daszak (born 1965)], whose group EcoHealth Alliance received some funding from PREDICT, lamented its loss at the time, arguing it's much cheaper for governments to stamp out small outbreaks than try to control a massive pandemic.

But there are some signs now, with the coronavirus pandemic in full swing, that funding to these crucial programs is coming back. PREDICT was granted an emergency six-month extension, and a new program, called Stop Spillover, is slated to launch in October.

And while it may be too late to stop this coronavirus in its tracks, scientists say the threat of the spillover event grows more imminent each year. As our population continues to expand, the interactions between humans and wildlife grow closer and closer. Cutting down forests and altering habitats push animals out of their own homes and deeper into human communities.

Poorly developed hygiene and sanitation systems can make it more likely for germs to build up. With humans and animals living in such close proximity, bacteria and viruses can easily jump from one species to another.

Once people become infected, the increasing interconnectedness of our world makes the spread of the disease easier. People and domestic animals are able to traverse the globe in a matter of hours. Illegal trade of exotic animals can move across borders undetected, carrying with them deadly bacteria and viruses.

"Several epidemiological drivers have been identified that make bacteria and viruses from animal populations suitable to emerge in a susceptible population. These drivers include climate change, industrial development, ecosystem change and social inequality," said Dr. John Brownstein, an epidemiologist, chief innovation officer at Boston Children's Hospital and contributor to ABC News.

So how do bacteria or viruses go from infecting animals to infecting humans?

One of the most common ways is coming into direct contact with the bodily fluids of an infected animal, such as a bat. This includes saliva, blood, urine and feces. Indirectly, people can come into contact with these through soil, plants, in animal habitats or by eating or drinking something that is contaminated.

Mosquitoes and ticks are two animals that are known to easily spread bacteria and viruses, including West Nile and Zika virus. After biting an infected person, mosquitoes and ticks are able to spread the virus to every subsequent person they bite.

According to [Dr. Tracey S. McNamara (born 1954)], rabies and plant diseases that can damage crops are the two diseases under surveillance in the United States.

"We don't think about it in the United States as much," said Dr. Christine Johnson, a professor of epidemiology and ecosystem health at the University of California--Davis School of Veterinary Medicine and director of the EpiCenter for Disease Dynamics. "There is a lot of active work to maintain vigilance for diseases. There is currently an outbreak of Ebola going on right now in the Democratic Republic of the Congo."

In Southeast Asia, efforts at identifying emerging diseases are focused on testing for viruses in both animals and people, especially in places where viruses can spill over, or find a new host, such as in humans, explained Daszak.

"We only know how to look for known diseases," said [Dr. Tracey S. McNamara (born 1954)]. Her vision is for a disease surveillance system to focus syndromes, a group of symptoms that are known to occur together.

By empowering veterinarians to share their findings with each other, McNamara hopes that this can help experts quickly identify the source of an outbreak before it spreads.

"Future efforts in zoonotic disease surveillance should include strong integration of animal and human agencies of health, including wildlife, agriculture and public health," added Brownstein.

• James M. Wilson V, MD is the Founder and Executive Vice President of AscelBio and Executive Director of Praecipio International. AscelBio, a for-profit corporation, provides consulting services to its clients for infectious disease risk assessments. Praecipio International is a nonprofit corporation dedicated to enhance and improve international public health and security against biological threats. Prior to his current position he was a Founder and the Chief Technical Officer / Chief Scientist of the Veratect Corporation in Seattle, Washington; Founder and Principal Investigator of Project Argus, Chief of the Argus Research Operations Center; and Division Head of Integrated Biodefense at the Imaging Science and Information Systems Center, Georgetown University. He was the concept, development, and operationalization lead for the new professional discipline of operational biosurveillance and lead architect and the founding member of the Biosurveillance Indication and Warning Analysis Community (BIWAC). Dr. Wilson received a Bachelor of Science in Applied Biology at the Georgia Institute of Technology, his medical doctorate from the University of Cincinnati College of Medicine, and trained as a pediatrician at Georgetown University Medical Center."

• Tracey S. McNamara, DVM is a Diplomate, A.C.V.P., Professor of Pathology at Western University of Health Sciences College of Veterinary Medicine in Pomona, CA.

• She graduated from the New York State Collegeof Veterinary Medicine at Cornell University. She served as senior zoo pathologist at the Bronx Zoo from 1987-2003 and held the Schiff Family Distinguished Scientist in Wild Animal Pathology endowed chair. Dr. McNamara specializes in the recognition and understanding of the diseases of captive and free-ranging wildlife and is best known for her work on West Nile virus. Her role in the discovery of the West Nile virus is described in the September 2000 GAO report “West Nile Virus – Lessons for Public Health Emergency Preparedness”,“Germs” by Judith Miller and “Secret Agents” by Madeline Drexler. In The Scientist (March 4, 2002), she is credited as having “served a central role as a unifying force, molding and sometimes forcing interrelationships between local and federal government agencies and private enterprises, enabling progress toward the common goal of monitoring a newly emerging disease in the United States.”

• Dr McNamara has served as a consultant to the National Biosurveillance Advisory Subcommittee and will be actively involved in the development of the Nation’s biosurveillance strategy through 2012. Most recently, she was asked to serve as lead on a project with Russian colleagues on the “Human-Animal Interface” by the Nuclear Threat Initiative’s Global Health and Biosecurity program in Washington DC.

In recent days, Europe has become the epicenter of coronavirus disease 2019 (COVID-19). Soaring case fatality rates across European states, disparate public health and global health security response across borders, baseline health-care infrastructure differences, and significant social, economic, and political influences on key decision-making all exacerbate the challenges of this acute crisis. As Europe moves into acute disaster response mode, a unified, oriented, and evidence-based crisis command must be established that goes beyond the established border measures taken and the European Union (EU) export scheme for protective equipment. We propose in this letter the EU mechanism for crisis managed response cycle be initiated immediately to mitigate preventable morbidity and mortality from coronavirus disease 2019 (COVID-19), which includes the North Atlantic Treaty Organization (NATO) and military alliance involvement.

Complete and comprehensive peer reviewed data related to morbidity and mortality for COVID-19 may not be available for many months and likely years. However, public health measures to flatten the curve of case fatality rates differ widely across the affected states and communities. In a maximal effort to defend civilian populations, communities, and regions, self-isolation, social distancing, multiple versions of quarantine, and even full lock downs have been instituted or considered in varying forms; some states may institute Martial Law. Social, economic, and political infrastructure are greatly tested across the EU, and health security once again demonstrates that disease observes no borders or passport color. Indeed, economic stress will come to a breaking point and confidence in European public health and democratic institutions will be greatly challenged; especially as we observe different responses, by individual countries, in the same union against the same coronavirus threat.

The EU Global Strategy points out that the EU is more and more facing hybrid forms of threats, and COVID19 tops the list today. However, the EU struggles to have a unified and integrated civil-military approach to public health crisis, disaster, and disease pandemic that is desperately needed immediately. The European Centre for Disease Prevention and Control (ECDC), an independent agency of the EU whose mission is to strengthen Europe’s defenses against infectious diseases, is closely monitoring the pandemic, providing risk assessments, public health guidance, and advice on response activities to EU Member States and the EU Commission. Within the domain of Civilian-Military interoperability, NATO, with locations throughout Europe, has multiple structures responding separately. The Force Health Protection Branch of the NATO Military Medical Center for Excellence (MILMED COE) is closely monitoring the developments. There are many NATO resources that can additionally be tapped to support the response. Health security intelligence, information sharing, and leadership with command decisions for the EU are completely absent.

Luckily, the EU has an application for that. The Council, or when an EU member state triggers the solidarity clause, can activate the EU Integrated Political Crisis Response Mechanism (IPCR); also referred to as the Crisis Platform, EU Situation Room, Crisis Management Board. This mechanism plays a central role in ensuring both swift and effective mobilization of actors and instruments across the entire EU system, as well as coherence of policies and actions throughout the various phases of the crisis life cycle. The Croatian presidency activated the IPCR in information sharing mode in January 2020 and triggered full activation mode on March 2, 2020.

However, in triggering this mechanism to its full extent, military and civilian resources, including the EU civil protection mechanism, will be liberated and under full command and direction from the Council and the European External Action Service (EEAS); multiple committees and commissioners and military staff would be forced to the table to respond in a unified voice. Full activation mode includes a united and clear structure for response and decision-making, de facto solidarity across the EU for crisis response. Beyond the integrated political crisis response mechanism as it is designed today, the EU, currently still including the United Kingdom, urgently requires a practical tool to analyze and fully apprehend the nexus between the different civilian and military (security and logistic) components of a crisis and disaster, as well as the determinant of the health/wealth concept that bound health systems to the political and economic dimensions of the EU.

As more data become available about case vitality rates, transmissibility, and overall natural history of disease for COVID19, the requirement to maximize information sharing on genomic, clinical, and outcomes will become more apparent. Triggering this crisis mechanism may also lead to further information sharing across platforms, public health infrastructure, socialized medical systems, and integrated with defense health structures. The time for action is now. The time for open and unified policy of how best to mitigate disease spread is required now. In order to provide economic, social, and political unity and confidence in democratic institutions of the EU, this must be done now.

Expansive coordination is essential for the EU, for the sake of both the individual nation states and the collective community. The model is applicable, however, beyond the boundaries of the EU. COVID19 is a global challenge, which mandates a global response. The precise coordinative mechanisms may vary, depending on national law and tradition, but the need for unity of effort has never been greater. Failure in this regard would exact a price, measured by the cost of millions of lives.

Introduction

• The West Nile virus epidemic in the Americas that spread coast to coast from 1999 to 2002 produced 48,183 documented cases and 2,163 fatalities (4.5%) across the United States by 2017 and gained permanent ecological establishment.1 The epidemic was the largest of its kind in the history of the western hemisphere.2 West Nile disease is caused by a mosquito-borne virus that, in a minority of typically older patients, causes encephalitis (brain infection) and other neurological problems such as paralysis, and death. The virus is capable of infecting multiple species of animals, including birds, horses, and reptiles. The crisis represented a ‘virgin soil’ epidemic, where a pathogen exotic to the receiving geographic area was introduced to an ecosystem that did not have appreciable levels of herd immunity. Herd immunity refers to the number of host individuals, across multiple species, that have protective immunity thanks to prior exposure to the pathogen. The impact of morbidity and mortality due to a given infectious disease is mitigated by the level of herd immunity, where lack of herd immunity implies the potential for explosive transmission and higher severity of illness.3
• The arrival of West Nile in the United States was initially recognized as an outbreak of bird die-offs and human encephalitis in New York City. The outbreak was eventually recognized as a prioritized warning signal through a complex, months-long, drawn-out pattern of siloed communications among disparate professional groups. Because of the unusual epidemiological and clinical presentation, discovery of a virus that did not morphologically match known endemic viruses, and recent social sensitization to the threat of biological terrorism, the situation was treated as a potential security threat.4
• This case study reviews the sequence of warning intelligence failures that contributed to delayed recognition, threat assessment, and loss of potential opportunity to mitigate the impact of this introduced exotic pathogen.

Materials and methods

• The authors utilized their own personal notes, government reports,5 and the narrative timeline compiled by Drexler (2003) to reconstruct the sequence of awareness among the organizations involved with alert and verification of the initial New York City outbreak of West Nile virus. For the media signal analysis, keyword queries were used for a media source local to New York City, the Daily News, to extract the number of references in an online curated newspaper archive, Newspapers.com.6
• Days of the crisis were numbered based on the first day of the month of first awareness, June 1999. To reconstruct preceding events in Europe and the Middle East, a review of peer-reviewed academic literature was conducted in the National Library of Medicine’s PubMed.7 To evaluate air traffic data between the Middle East and the United States, data were analyzed from the US Department of Transportation Bureau of Transportation Statistics.8

Results

• In the summer of 1996, an unusual epidemic of West Nile virus was reported in Romania, where officials from the US Centers for Disease Control and Prevention were invited to assist with the investigation.9 It was believed to be the first documented large-scale epidemic in Europe involving human patients. Nearly 400 human patients were identified with 17 deaths and evidence of virus in local mosquito and bird populations. In the subsequent years, West Nile virus was found to have spread regionally, with additional human cases in the Czech Republic in 1997 and identification in horses in Italy and a large epidemic involving swans in Israel in 1998.10 The swans in Israel were believed to have picked up the virus during their seasonal migration from West Nile-infected areas of Europe.11 Overall, it appeared there was a new wave of virus transmission in Europe- an evolution of West Nile introduction to Europe since the 1960s from Africa, where it was previously endemic.
• In June 1999, a private veterinary clinic in Bayside, Queens, New York City evaluated wild crows brought to the facility by local community citizens who were concerned the birds were acting strangely.12 There was no indication the clinic was able to diagnose the disease or environmental exposure responsible. These cases of wildlife disease were not reported to local health authorities.
• In early August, the New York State Department of Environmental Conservation (NYSDEC) received reports of bird die-offs involving crows in New York City parks. The NYSDEC was the state agency responsible for wildlife disease evaluation.13 On August 9th (Day 69), dead wild crows were discovered outside the Queens Zoo property and reported to one of the authors (McNamara).
• McNamara served as the head veterinary pathologist for the parent organization for the Queens and Bronx Zoos as well as three additional zoos in the New York City area. McNamara, noting dead crows as well at the Bronx Zoo submitted samples to the NYSDEC. On August 12th, a report of no diagnosis was returned to the curator of the Queens Zoo. This caused consternation among the zoo’s leadership due to the potential for an unknown disease to cause illness and death among both zoos’ collections of exotic birds. Three days later, the first human patient was admitted to Flushing Hospital, Queens with undiagnosed, severe illness.14
• On August 17th, the NYSDEC wildlife pathologist examines crow specimens however is unable to diagnose what killed them. On August 19th, McNamara was notified the Bronx Zoo samples also returned a result of no diagnosis. The NYSDEC wildlife pathologist was receiving many dead bird specimens, according to the local media the same day. On approximately August 20th, a Bayside, Queens local neighborhood newspaper reported crow die-offs, asking if ‘. . .a plague hit the Bayside area?’15
• On August 23rd (Day 83), an infectious disease physician at Flushing Hospital notified local public health officials of two unusual cases of encephalitis and paralysis that were admitted to the intensive care unit. This included the patient admitted on August 12th.16 Simultaneously, McNamara sent brain tissue samples from dead wild crows to the New York Department of Environmental Conservation. McNamara was not satisfied with the lack of diagnosis and began her own investigation. Her review of the samples in her laboratory indicated the presence of a possible viral encephalitis to explain the crow deaths.
• Two more cases of encephalitis were admitted to the Flushing Hospital intensive care unit and two additional cases were admitted to another local hospital on August 27th. This was an unusual volume of encephalitis cases. The next day, local public health authorities arrived at Flushing Hospital while a fifth case was admitted. On August 29th (Day 89), local public health officials notified the US Centers for Disease Control and Prevention as an emergency communication. Two days later, Saint Louis Encephalitis (SLE) virus was identified in samples from the Flushing Hospital patients at a local New York public health laboratory; these samples were shipped to the CDC arbovirus laboratory in Fort Collins, Colorado for verification.17 SLE virus is a known, endemic mosquito-borne virus in the United States. Paralysis was not previously reported for endemic SLE infections in the United States. Prior seasons of SLE transmission in the United States began in the southern states with northward progression versus initial appearance in northern states. The southern warning signal did not precede this crisis.18
• On September 3 (Day 94), New York City local public health were notified by CDC-Fort Collins of a confirmed diagnosis of SLE virus and initiated mosquito spraying. City officials communicated with the Federal Bureau of Investigation to report a possible act of biological terrorism. The next day (see Figure 1), local public health officials began speculation about a link between the bird die-offs and human cases. At this point, McNamara became aware of local news media attention on an unusual encephalitis outbreak involving human patients.19
• McNamara called CDC-Fort Collins on September 9th (Day 100) with concerns the SLE diagnosis did not fit the epidemiological pattern she was seeing- a bird die-off. This was in the context of increased zoo employee anxiety about their risk of exposure to disease still killing the exotic bird population. SLE transmission did not cause bird die-offs based on prior experience with the virus in the US. Other viral avian diseases such as highly pathogenic avian influenza and Newcastle disease would have killed the zoo’s chickens in the petting zoo area, and Eastern equine encephalitis would have killed the emus present in the park. These avian populations were spared, highlighting another epidemiological and clinical pattern that did not fit the initial SLE diagnosis. These birds would have served as sentinels for known causes of encephalitis in birds in the western hemisphere. The observation they were not dying indicated the possibility of a novel, previously unrecognized veterinary pathogen.
• McNamara relayed concern that one of the Bronx veterinarians had accidentally stuck themselves with a needle while euthanizing a symptomatic flamingo. McNamara was advised that CDC did not process samples from animal species and did not share McNamara’s concern that the epidemiological pattern did not make sense. McNamara proceeded to send samples to the National Veterinary Services Laboratory at the US Department of Agriculture in Ames, Iowa. Two days later, the National Veterinary Services Laboratory called McNamara to report the avian samples were positive for a flavivirus, but no additional specific identification information was available. This was an unprecedented laboratory finding from the veterinary perspective- no flavivirus had been known to cause animal disease in the western hemisphere. The flavivirus family includes dengue, yellow fever, SLE, and West Nile virus species. McNamara notified CDC-Fort Collins, again emphasizing the pattern of transmission may not be SLE virus. The National Veterinary Services Laboratory forwards McNamara’s samples to CDC for further testing.
• In the third week of September, the Connecticut Agriculture Experimental Station identified flavivirus in both crow and mosquito samples, unbeknownst to McNamara. On September 21st, McNamara spoke with the U.S. Army Medical Research Institute for Infectious Diseases (USAMRIID) at Fort Detrick, Maryland and sent them samples. USAMRIID confirmed flavivirus in McNamara’s samples and ruled out SLE virus on September 22nd (Day 113). That same day, CDC-Fort Collins identified flavivirus virus from McNamara’s samples that were sent two weeks previously to the National Veterinary Services Laboratory. The last known West Nile-positive human patient was ill also on September 22nd. On the next day, an academic researcher, Ian Lipkin, identified flavivirus from New York City human brain samples and communicated that finding to the New York State Department of Health. CDC-Fort Collins retested human samples and revised their diagnosis to West Nile virus.20
• On September 24th, Lipkin informed the NYSDEC the virus genetic sequences most closely matched Kunjin or West Nile virus. That same day, CDC notified the New York State Department of Health the bird samples were positive for West Nile, and Lipkin discovered positive West Nile virus genetic sequences in human samples. The next day (Day 115), the media reported the presence of West Nile in New York City’s birds.21
• The New York City media reporting signal began on September 4th (Day 95), with a report of an outbreak of St. Louis encephalitis (Figure 1). The transition in terminology to West Nile occurred on September 25th (Day 115), which was the day of first mention of crow die-offs in the media source used for this study. Human illness was reported before bird die-offs and to a more robust degree. The media signal was approximately three months from local community notation of the first indicators of crow deaths in June. The online newspaper archive used for this study, which reported on New York City writ large, did not make note of the local Queens community paper’s report of an unusual outbreak of disease in crows in late August 23.22
• Data from the Bureau of Transportation Statistics acquired in 2003 by one of the authors (Wilson) indicated the leading source of air traffic from the Middle East to New York City and Newark, New Jersey in 1999 was Israel, which seasonally peaked in August (Figure 2). There were, on average, 50,700 passengers that traveled between New York City and Israel in 1999.23 The Bureau indicated to Wilson no public health official had asked for air traffic data – that this was the first time to their recollection any public health official had asked for such data for any outbreak investigation. In 2001, the origin of the epidemic was reported to be Israel.24 The mechanism of virus translocation to the United States, whether importation of infected mosquitoes or human passengers, was not proven.

Discussion

• This case study highlights the challenges of integrating and maintaining a system of strategic health security warning intelligence with near-real time local warning communications. Unfortunately, reports of unusual West Nile activity in Europe did not result in a focus on preparedness in the United States. Connectivity between unusual West Nile activity in swans in Israel was not reported until years after the epidemic in New York City, and the air traffic connections between the United States and Israel were not known at the time. This information might have enabled focused warning communication to New York City and proactive preparedness activities such as mosquito spraying at the airports and education of veterinarians and healthcare clinicians. It is unknown whether proactive mosquito spraying at the airports would have stopped translocation of the virus to the western hemisphere. Israel did not have an established surveillance system for West Nile and thus was not a reportable human disease- this was created after the well-publicized New York epidemic. In 2001, Israel mandated reporting of West Nile infections in humans.25
• Delays in unusual disease signal recognition result in delays in public health engagement, whether those signals appear in animals or in humans. It is arguable that, had McNamara not pushed for recognition of an animal signal that appeared at the same time as a human signal, the world would have drawn the conclusion that the New York epidemic was due to a routine mosquito-borne virus, Saint Louis encephalitis (SLE). McNamara did not know of the human signal until it was announced by the media on September 3rd, which highlights a missed potential opportunity of connecting the bird die-offs with human cases two weeks prior. There were important differences in threat assessment of a known, endemic disease (SLE) for which there was a given baseline of herd immunity versus an exotic disease (West Nile) where there was little to no herd immunity. Epidemics involving known, endemic disease implies routine public health response. Alternatively, virgin soil epidemics imply emergency response and potential for threat to national security. These situations suggest involvement of agencies involved with national defense or attribution investigation if there is suspicion of biological terrorism. Regardless of etiology, virgin soil epidemics are also often associated with greater socio-economic disruption to the involved communities than epidemics involving routine, locally familiar disease.
• The critical role of the astute clinician-observer was highlighted in this case study with the involvement of the infectious disease physician at Flushing Hospital and McNamara at the Bronx Zoo. Had the local veterinarian in Bayside, Queens reported the apparent outbreak of unusual disease in crows in June, they too would have represented another astute observer. The presence of astute observers does not fully solve the challenge of recognition; however, the first known human case was missed, an unrecognized case that presented on August 2nd.26 This highlights the value of experienced observers well trained in considering both routine and non-routine diseases among their patients. It also highlights the value of education and training in the recognition of rare diseases and pathogens of concern for potential use as potential biological weapons.
• There were multiple community organizations, professional disciplines, and associated governmental agencies that exhibited siloed communication that interfered with timely recognition of the threat signal. These groups included: human health clinicians; community and exotic animal veterinarians; diagnostic laboratories including both veterinary and human health and spanning both military and civilian agencies; community special interest groups (i.e., in Queens that brought crows to the veterinary clinic); and public health authorities.
• We estimated there were at least nine separate groups of people that together contributed to the final recognition and diagnosis of West Nile virus during this epidemic, of which two astute observers played key roles in initiating the warning sequence of communication. There was evidence of bias at CDC when they believed SLE virus was initially responsible for the epidemic, and when questioned about their belief exhibited resistance to the presentation of competing hypotheses relating to discrepancies in epidemiological and clinical patterns of disease relating to both the avian and human cases.
• There was evidence of bias in social sensitivity that ultimately prioritized public orientation to a threat signal and mount organized, emergency response. The driver for public health engagement was report of human versus animal disease. It is debatable whether public health would, or politically could, have engaged in response with report of a possible outbreak of disease in crows in June –  unless a flavivirus unknown to the western hemisphere could have been diagnosed in June. This implies caution when considering research demonstrating the appearance of high threat infectious disease in animals preceding appearance in humans. Public perception and reaction to that perception may be focused on human disease as validation of threat, which highlights the challenges of integrating veterinary and human health disease surveillance to produce effective warning communication in health security.
• There is caution in the use of open-source intelligence for warning signals related to health security threats. Warning signals associated with health security crises are often associated with significant delays in public communication. These delays are typically related to lack of local familiarity with the pathogen in question and therefore no prior investment in a specific, established public health surveillance system for the given pathogen.
• Currently, the American system of biological threat warning does not include a robust wildlife diagnostic surveillance component. In addition, animal sentinels found in crowded urban centers like dogs, cats, and shelter animals and zoological collections do not fall under the jurisdiction of any federal agency and therefore are not currently under any formal surveillance. Should a similar warning signal appear in these sentinels, it is possible they would be missed. Even if this component existed, there remain significant communication defects between the veterinary and human health communities and the federal and private sectors.
• As with other health security crises, there is often no available pharmaceutical countermeasure to mitigate impact. As of the date of this writing, there is no FDA-approved human vaccine for West Nile virus, nor is there an approved anti-viral. Education and mosquito control remain the mainstays of impact mitigation, which emphasizes the importance of early warning to prompt non-pharmaceutical countermeasures. Regardless of concerns about attribution, early warning coupled to proactive preparedness and response is crucial to mitigate the effects of health security threats.

Notes

1. 1. Centers for Disease Control and Prevention, “West Nile Virus.”
2. 2. Centers for Disease Control and Prevention, “Provisional Surveillance Summary.”
3. 3. Crosby, “Virgin Soil Epidemics.”
4. 4. U.S. Government Accountability Office, “West Nile Virus Outbreak.”
5. 5. Ibid.
6. 6. Newspapers.com.
7. 7. PubMed.gov.
8. 8. Bureau of Transportation Statistics, “Air Carriers.”
9. 9. Tsai et al., “West Nile Encephalitis.”
10. 10. Hubálek and Halouzka, “West Nile fever”; Hubálek, Halouzka, and Juricová, “West Nile fever”; and Giladi et al. “West Nile Encephalitis.”
11. 11. Malkinson et al., “Introduction of West Nile.”
12. 12. Drexler, Secret Agents, 32.
13. 13. See note 5 above.
14. 14. Ibid; and Drexler, Secret Agents, 20.
15. 15. See note 5 above.
16. 16. Drexler, Secret Agents, 20.
17. 17. See note 5 above.
18. 18. Drexler, Secret Agents, 56.
19. 19. See note 5 above.
20. 20. Ibid.
21. 21. Ibid.
22. 22. See note 7 above.
23. 23. See note 9 above.
24. 24. Giladi et al., “West Nile Encephalitis.”
25. 25. Ibid.
26. 26. See note 5 above.

Acknowledgements

• The authors gratefully acknowledge the manuscript reviewers for their comments.

Disclosure statement

• Dr. Wilson is employed by M2 Medical Intelligence.

Notes on contributors

• Tracey McNamara, D.V.M., Diplomate, A.C.V.P., NAPf is a veterinary pathologist and a Professor of Pathology at Western University of Health Sciences College of Veterinary Medicine in Pomona, CA. Dr. McNamara specializes in the recognition and understanding of the diseases of captive and free-ranging wildlife and is best known for her work on West Nile virus. Dr. McNamara served as a consultant to the National Biosurveillance Advisory Subcommittee and continues to be actively involved in the development of the Nation’s biosurveillance strategy. She served as lead on a project with Russian colleagues on the ‘Human-Animal Interface’ by the Nuclear Threat Initiative’s Global Health and Biosecurity program in Wash. DC. She recently gave a TEDxUCLA talk entitled ‘Canaries in the Coalmine’ about continued gaps in biosurveillance for emerging biological threats. She is a founding member of the Global Health Security Alliance (GloHSA) group established by the German government in 2017. Most recently, she participated in Ending Pandemics ‘Finding Outbreaks Faster – Metrics for One Health Surveillance’ at the Salzburg Global Seminar in Austria and is now a Salzburg Global Seminar Fellow. She is actively involved in the One Health movement and advocates for a species neutral approach to the detection of pandemic threats.
• James M. Wilson is the CEO of M2 Medical Intelligence, Inc. Dr. Wilson is a board-certified, practicing pediatrician who specializes in operational health security intelligence, with a focus on the anticipation, detection, and warning of infectious disease crises. Dr. Wilson led the private intelligence teams that provided tracking of H5N1 avian influenza as it spread from Asia to Europe and Africa, detection of vaccine drifted H3N2 influenza in 2007, warning of the 2009 H1N1 influenza pandemic, discovery of the United Nations as the source of the 2010 cholera disaster in Haiti, and several investigations of alleged and confirmed laboratory accidents and biological weapon deployments. Dr. Wilson is a strong advocate for effective and accountable global health security intelligence and the need for credible and balanced threat assessments.